'طرق التحليل الانشائى للاستخدامات البحريةة للمنصات


(system) #1

( بسماللهالرحمنالرحيم)

COLOR=#000000 لِيَجْزِيَهُمْ اللَّهُ أَحْسَنَ مَا عَمِلُوا وَيَزِيدَهُمْ مِنْ فَضْلِهِ وَاللَّهُ يَرْزُقُ مَنْ يَشَاءُ بِغَيْرِ حِسَابٍ ([/color]38) وَالَّذِينَ كَفَرُوا أَعْمَالُهُمْ كَسَرَابٍ بِقِيعَةٍ يَحْسَبُهُ الظَّمْآنُ مَاءً حَتَّى إِذَا جَاءَهُ لَمْ يَجِدْهُ شَيْئاً وَوَجَدَ اللَّهَ عِنْدَهُ فَوَفَّاهُ حِسَابَهُ وَاللَّهُ سَرِيعُ الْحِسَابِ (39) أَوْ كَظُلُمَاتٍ فِي بَحْرٍ لُجِّيٍّ يَغْشَاهُ مَوْجٌ مِنْ فَوْقِهِ مَوْجٌ مِنْ فَوْقِهِ سَحَابٌ ظُلُمَاتٌ بَعْضُهَا فَوْقَ بَعْضٍ إِذَا أَخْرَجَ يَدَهُ لَمْ يَكَدْ يَرَاهَا وَمَنْ لَمْ يَجْعَلْ اللَّهُ لَهُ نُوراً فَمَا لَهُ مِنْ نُورٍ (40)

* صدق الله العظيم *

( 24 - سورة النــور )

[LEFT][RIGHT]Edit by alaa refit waheed hekail bhit 5th civil departement2007©

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[RIGHT]contents

CHAPTER 1

HESTORICAL OVERVIEW of offshore structure

CHAPTER 2

GENERAL INTRODUCTION OF OFFSHOER STRUCTUER

CHAPTER 3

KIND OF OFFSHOER STRUCTUER

CHAPTER 4

GENERAL INTRODUCTION OF TLP OFFSHOER STRUCTUER

CHAPTER 5

TENSION LEG PLATFORM SYSTEM

CHAPTER 9

INTERNET SITES[/right]

[LEFT][RIGHT]Edit by alaa refit waheed hekail bhit 5th civil departement2007©

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[RIGHT]CHAPTER 1

Index

HESTORICAL OVERVIEW of offshore structure[/right]

[LEFT][RIGHT]Edit by alaa refit waheed hekail bhit 5th civil departement2007©

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HESTORICAL OVER VIEW

The beginning of the story of the remarkable offshore concrete structures is only 30 years behind us. When the petroleum industry established activities in the North Sea in the late sixties, an immediate reaction from the Norwegian construction industry was that concrete should be able to compete with steel, that had been the traditional structural material in this industry (Fjeld and Morley, 1983), (Moksnes, 1990), (Gudmestad, Warland, and Stead, 1993). This assumption proved to be true regarding the cost of the structure as well as the maintenance costs.
One after the other of spectacular structures, 22 in total, have been placed on the sea bed in the North Sea reaching up to 30 m above sea level and down to 303 m at the deepest location, making this structure one of the tallest concrete structures in the world (Holand and Lenschow, 1996).
The most innovative period was around 1970, when the Ekofisk concrete platform was towed to its location, and the first of the many Condeep platforms was on the drawingboard.

( The Ekofisk tank, completed 1973 (by courtesy of Aker Maritime )

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Offshore concrete structures have proved to represent a competitive alternative for substructures in the North Sea and in other places where large offshore structures for production of oil and/or gas are required. The deep Norwegian fjords have represented a particular advantage during the construction phase, as the substructures here can be lowered deep into the sea, enabling the production plant to be floated on barges over the platform for transfer to the substructure. Hence, the production plant can be completed at quay side where the productivity is best. Hereby, costly offshore heavy lifting and hook-up activities are avoided.
Furthermore, offshore concrete structures have proved to be highly durable and to have good resistance against corrosion (Fjeld and Morely, 1983), provided that the concrete is dense, have a minimum of cracks and sufficient cover over the rebars. The Norwegian Standard NS 3473 requires 40 mm for permanently submerged parts and 60 mm in the splash zone. In the North Sea even larger rebar covers have normally been used.
Recent concrete projects are:
· in the Netherlands: F3, concrete gravity base 1992
· in the North Sea, Norwegian sector: Troll gas fixed platform, Heidrun tension leg platform and Troll oil catenary anchored floating oil platform , all completed in 1995
· in the North Sea, British sector: The BP Harding Gravity Base Tank completed in 1995
· in Congo: N’ Kossa, concrete barge 1995
· in Australia: Wandoo B, Bream B, West Tuna, concrete substructures completed 1996
· on the Canadian continental shelf outside Newfoundland: Hibernia 1997
· in the North Sea, Danish sector: South Arne, to be completed in 1999.

Edit by alaa refit waheed hekail bhit 5th civil departement2007©

Although the recent development has not favoured concrete platforms, there are several concept studies ongoing in the design offices. As promising floater concepts, new generations of tension leg platforms and a concrete Spar shall be mentioned. (Chabot, 1997), (Brown and Nygaard, 1997).

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[RIGHT]At present work is ongoing to develop more cost-efficient concrete structures for development of smaller hydrocarbon fields. The F3 field in the Dutch offshore sector, mentioned above, is an example; a concrete structure installed at Ravenspurne North in the British sector is another.
Design concepts

1- Cylindrical tanks:-

The first concrete platform was the Ekofisk platform, that was built according to a French-Canadian concept and completed in 1973.
The decision to launch the Ekofisk platform made way for the development, not only of offshore structures but also for a development of the concrete material, design methods, construction methods, load predictions, quality management and safety evaluations.
Three additional designs in the North Sea followed mainly the Ekofisk concept (Frigg CDP­1 1975, Frigg MP-2 1976 and Ninian Centre 1978) (FIP, 1996). The huge platform built by Mobil at the Hibernia field in Canadian waters and completed in 1997 is also mainly of the same type
2- Condeeps and similar gravity based structures:-
the Condeep,which became the winning concept for a period of time, was based on a cellular base with circular cells and one to four hollow columns (shafts), and thus had the advantage of a slim shape through the wave zone. Beryl Alpha, the first Condeep platform, was placed on the UK continental shelf in 1975. Up to 1995 a total of 14 Condeeps have been installed in the North Sea (Agnes, 1997). shows the largest of these structures .
Other designs were based on the same principles, except that the cells in the raft were rectangular (four platforms in the North Sea completed 1976-78, and also BP Harding in UK waters, 1995, and South Arne on Danish Continental shelf, 1999)
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(Bassoom) #2

ممكن توضيح ؟
اتكلم قول حاجة !


(مُحمَّد) #3

اللهم وفقنا الى ما تحب وترضى


(system) #4

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(system) #5

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